The present invention related to an injection anchor adapted to be placed in pre-drilled holes, with the anchor including a tube having a closed end and provided with at least one radial exit hole for injection material and an elastic jacket for enclosing the tube.
In, for example, Bebrauchsmuster 70 24 434 an injection anchor is proposed including a smooth-walled tube provided with round or elongated hole-like exit holes for enabling an injection of the injection material, whereby a reinforcing wire is wound around the tube, with the reinforcing wire being fixed by rings surrounding the tube and connected with the tube. On one portion of a length the tube and/or protective casing thereof, an elastic jacketing--for example, hollow block stones or ventilated bricks--prevent the injection material from creeping uncontrolled into hollow cavities. However, the proposed injection anchor is, due to a multi-part construction thereof, relatively expensive to produce and cumbersome to handle. When the proposed injection anchor is slid into a drill hole, the external jacket slips, so that it loses a blocking or locking function with respect to the hollow spaces on the masonry side. Additionally, the resistance of the smooth-walled tube to an extraction from the injection stopper is very limited.
Other injection anchors have been proposed which include a solid material rod, having either a drilled injection canal or capillary tubes running adjacent an outside of the anchor rod. However, a disadvantage of the proposed injection anchors resides in the fact that they are relatively expensive to produce.
The aim embodying the present invention essentially resides in providing an injection anchor capable of being mass produced at a reasonable price, as well as an injection anchor which is easy to handle and has a high resistance to extraction--, with regard to both the whole injection stopper from the pre-drilled borehole as well as in terms of pulling the tube out of the injection stopper.
In accordance with the present invention, the tube is provided with diametrically opposed rounded-off indentations over an entire length thereof, and includes alternating flat-oval cross-sectional areas and substantially rounded cross-sectional areas, with an elastic jacket being shaped as a hose extending over a length of the tube, and with the elastic jacket being tucked in at each of its ends into the tube ends and solidly clamped to the tube by, for example fastening members.
In accordance with the present invention it is possible to manufacture the anchor out of only a few parts, such as, for example, for the tube, cross-cut pieces of commercial tubes and for the elastic jacket, cross-cut hose pieces can be used, with the jacket advantageously including a textile fabric or weave that can be expanded to a certain extent. The tube and jacket are securely attached to one another using simpler, rivet-like fasteners, so that the jacket cannot slip when inserted into a borehole. When the injection material is being injected, the jacket is pressed against the drill hole wall, while the injection material passes through the jacket having a limited permeability for the injection material, so that an adhesive bond is achieved with the borehole wall. The jacket thereby bulges out in a formed hollow cavities so that the injection stopper is held in a form-closed manner in the masonry or a like material.
Because of the many indentations in the tube, the tube is seated in a form-closed manner in the injection stopper formed on the inside and outside of the tube, so that the tube itself has a high resistance to extraction. Through the indentations, the tube experiences an outward distension of the material so that the undulating tube does not re-deform, even under high tension loads. The injection anchor may consequently be manufactured as an inexpensive mass-production article in lengths of up to several meters and with diameters of several centimeters, such as, for example, five centimeters, and is foolproof in terms of handling and use.
According to the invention, the tube, in an area of the opposed indentations, is reduced to about one-half a diameter thereof and the tube is continuously undulated avoiding sharp edges. With such an arrangement, localized capacity loads are avoided when traction or thrust loads are brought to bear, so that the danger of breaking the tube or the injection stopper is prevented.
Advantageously, on both ends the same rivet-like fasteners are used which have a passage channel in which the locking piece is pressed into the rear fastener, which, consequently, improves the solid clamping of the tucked-in hose end to the tube.
According to the present invention, at the front end of the anchor the tucked-in hose is provided with an end section extending into the tube by a shaft portion of the fastener which functions as a back-pressure valve when laying aside the injection device and which prevents the injection material from escaping.
According to further features of the present invention the tube is provided at a back end thereof with a larger exit or discharge hole and smaller exit holes distributed over a length thereof. By this arrangement, it is ensured that, on the one hand, the injection material exits into the borehole space near the back end of the injection anchor and gradually fills the borehole space from back to front, and on the other hand, with particularly quick-setting injection materials, it is ensured by virtue of the provision of small holes in the front that the entire borehole space is filled with injection material.
In accordance with still further advantageous features of the present invention, a positioning gasket is clamped between the rivet head of each fastener and the tube ends, with the positioning gasket being adapted to a diameter of the borehole. By virtue of the provision of the positioning gasket a coaxial alignment of the injection anchor to the borehole is ensured.
It is also possible in accordance with the present invention to provide connector posts that are adapted to be plugged into the tube of the injection anchor, and a front portion having a with the connector post being, for example an external screw thread. The connector posts are inserted into the tube prior to a complete hardening of the injection material and a protruding end of the connector post can be used in a manner appropriate to its structure as a hook, eyelet, etc. for reinforcing or suspending other structural pieces.
A further advantage of the present invention is that the tube may be undulated in at its front end, the fastener may be inserted into the tube with high clamping force and its shaft may be provided with an inner thread bore. This allows for mass production of anchors having a highly stable fit of the fastener on the tube, so that the tensile strength with which the fastener can be extracted from the tube, using an appropriate tool, is equal to or somewhat greater than the minimum extraction resistance of the injection anchor. Therefore it is possible to test the extraction resistance of the injection anchors by withdrawing the front fastener from the tube to ascertain whether the injection anchors have prescribed extraction resistance.
In another embodiment of the present invention the tube of the injection anchor may be provided, with diametrically opposed, rounded-off indentations so that the tube has alternating flat-oval cross-sectional areas and substantially round cross-sectional areas over the length of the tube excluding the end sections. The tube jacket may be constructed as a longitudinally elastic hose or sock which is secured on one end to the insertion end of the tube and on the other end is secured to a shrouding ring displaceably mounted to a front segment of the tube.
The injection anchor of the present invention can be inserted either completely into a borehole or left protruding out to a predetermined extent where its end may be used for connecting further elements such as, for example, attachment to a bracket.